Xonotic is an open-source first-person shooter video game. It was developed as a fork of Nexuiz, following controversy surrounding the game's development. The game runs on a heavily modified version of the Quake engine known as DarkPlaces engine. Gameplay is inspired by Unreal Tournament and Quake, but with various unique elements. Xonotic's stated aim is to become the best possible fast-paced open-source FPS.